1. Field
Embodiments of the present invention generally relate to apparatus and methods for refurbishing an electrostatic chuck. More specifically, to repairing a severed electrical connection in the balancing circuit of an electrostatic chuck.
2. Description of the Related Art
In substrate processing equipment, an electrostatic chuck is commonly used for clamping a substrate to a pedestal during processing. The electrostatic chuck clamps the substrate by creating an attractive force between the substrate and the chuck. A voltage is applied to one or more electrodes in the chuck to induce oppositely polarized charges in the substrate and the electrodes, respectively. The opposite charges pull the substrate against the chuck, thereby retaining the substrate.
In a bipolar, electrostatic chuck, a chuck body has a pair of coplanar electrodes embedded therein. Each electrode is respectively connected to a terminal of a dual power supply having a common terminal, which is referred to as a center tap. The center tap is connected to a substrate spacing mask provided on the surface of the chuck in order to balance any variations in the impedance between the substrate and the electrodes. Thus, a constant electrostatic attraction force between the substrate and the chuck is maintained across the surface of the chuck.
The electrical connection between the center tap and the substrate spacing mask is often made through the conductive wall of a gas conduit used to supply gas to the backside of the substrate during processing. The gas conduit is attached to a metalized central bore within the chuck body. This connection works well during substrate processing, but the conductive connection is sometimes disrupted or otherwise compromised over time. While the conductive connection may remain mechanically sound, the connection may not be effectual in conducting electric current, which results in improper or dysfunctional operation of the electrostatic chuck.
Conventional repair methods include re-establishing the conductive connection using welding techniques, such as electron beam welding or laser welding techniques. However, these methods are expensive and time consuming, which increases cost of ownership and extends chamber downtime.
Therefore, a need exists for apparatus and methods of restoring a compromised balancing circuit electrical connection in an electrostatic chuck.